DW is transparent enough to publish the negative returns from bad years so he definitely lost money in some years , but like I said "time in market" is better than "market timing" so one should look at multi-year returns. DW publishes his annual XIRR so it looks like over a longer term, he is doing fine.
I also lose money in some years and make money in some years, but overall I'm doing fine, roughly 8-9% CAGR. I'm sure there are others with double digit CAGR, but I'm happy with high single digit.
One of my big loser shares would be SPH, but when I calculated the CAGR including dividends, it was still 4% CAGR over 10+ years - which is not great, but the idea of owning a diversified portfolio of shares is that the winners balance the losers. So imagine that, even if you went all in and bought a loser share like SPH around the GFC period, your 4% CAGR will still be better than leaving it in fixed deposit
But most people can do better than owning SPH. I have elderly relatives who are very conservative and risk adverse, and the only shares they own are the local banks DBS, UOB, OCBC, because they have blind faith in the local banks. It actually turned out pretty well for them.
If you backtested your portfolio since GFC by calculating your returns if you bought shares instead of leaving in cash, I think you would also realise that your $1m will be $2m today simply by randomly choosing 30 shares that are part of a major stock market index for example (or buying property, because buy property in Singapore sure huat!)